1. Field
The following description relates to a backlight unit, a three-dimensional (3D) display having the same, and a method of forming a 3D image. More particularly, direction of light emitted by the backlight unit may be adjustable.
2. Description of the Related Art
Three-dimensional (3D) images can be formed according to the principle of stereo visualization in a viewer's eyes. An important factor in generating a stereoscopic sensation in 3D images is the binocular parallax which occurs due to the distance between two eyes of the viewer (i.e. about 65 mm). There are generally two different types of conventional three-dimensional (3D) image displays. A first type of 3D image display requires suitable glasses to see 3D images on the display, and a second type of 3D image display does not require glasses to view 3D images. In the second type of 3D image displays, 3D images can be generated by separating right images and left images without using glasses. Techniques for the 3D image displays without 3D glasses include a parallax barrier method and a lenticular method.
In the parallax barrier method, images to be observed by right and left eyes are alternately displayed, where each image has longitudinal patterns, and the images are observed using a very thin longitudinal lattice row, e.g., a barrier. In this way, a longitudinal pattern image for the left eye and a longitudinal pattern image for the right eye are separated by the barrier. The image for the left eye and the image for the right eye have different view points, and thus they are separately observed by the right and left eyes, respectively, to form a stereoscopic image.
In the lenticular method, images corresponding to right and left eyes are disposed on a focal plane of a lenticular lens, and the images are observed through the lenticular lens. The images corresponding to the right and left eyes are divided based on the characteristic of the lenticular lens, and thus they are separately observed by the right and left eyes, respectively, to form a stereoscopic image.
In both the parallax barrier method and the lenticular method, a stereoscopic image viewing area is fixed because a barrier or lens, a focal length, an emission direction, and the like are fixed. For example, a 3D image can be viewed only either in a landscape/horizontal mode or in a portrait/vertical mode of a display in the parallax barrier and lenticular methods. This is because the barrier and lenticular lens are arranged such that only a certain display direction and orientation provides images that the right and left eyes can properly observe in order to form a stereoscopic image.